On Thu, Sep 14, 2017 at 11:42:38PM +0000, Darrell Ball wrote:
>
>
> On 9/5/17, 2:23 AM, "Yuanhan Liu" <y...@fridaylinux.org> wrote:
>
> This patch associate a flow with a mark id (a uint32_t number) by CMAP.
>
> It re-uses the flow API (more precisely, the ->flow_put method) to setup
> the hw flow. The flow_put implementation then is supposed to create a
> flow with MARK action.
>
> Co-authored-by: Finn Christensen <f...@napatech.com>
> Signed-off-by: Yuanhan Liu <y...@fridaylinux.org>
> Signed-off-by: Finn Christensen <f...@napatech.com>
> ---
> lib/dpif-netdev.c | 85
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> lib/netdev.h | 6 ++++
> 2 files changed, 91 insertions(+)
>
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index 071ec14..f3b7f25 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -446,6 +446,12 @@ struct dp_netdev_flow {
> const unsigned pmd_id; /* The 'core_id' of pmd thread owning
> this */
> /* flow. */
>
> + const struct cmap_node mark_node; /* In owning
> dp_netdev_pmd_thread's */
> + /* 'mark_to_flow' */
> + bool has_mark; /* A flag to tell whether this flow has
> a
> + valid mark asscoiated with it. */
> + uint32_t mark; /* Unique flow mark assiged to a flow */
>
>
> [Darrell] Since the PMD that receives a flow can change and multiple PMDs can
> allocate
> the same mark value at the moment, it seems the mark allocation needs to
> include the PMD ID or
> be from a global namespace to enforce uniqueness.
> Pls verify.
Yes, you are right. Let it be global then. Talking about that, one of my
colleague actually suggests to use an array to do the mapping. It's a
"number -> flow" mapping after all: using a hash map looks like an overkill.
Using array also would give us the best performance.
The reason I chose cmap in the beginning is we don't know how big the
array is. Also, it doesn't make sense to allocate a static array big
enough to hold the maximum entires (it's uint32_t after all).
So I'm now thinking:
- allocate a small array first, say with 1024 entries
- if there is no space, double the max (say, 2048) and re-allocate
I don't know the performance difference yet. I will get back to you
when I have the number. Besides that, what do you think.
--yliu
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